The Missing Semester of your CS Education

Topic 1: The Shell. missing.csail.mit.edu .

What is the Shell?

At their very core, shells are all roughly the same: they allow you to run programs, give them input, and inspect their output in a semi-structured way.

Potpourri of Shell Utilities and Programs

We can find out which file is executed for a given program name using the which program, e.g. $ which python gives me /Users/dchege711/anaconda3/bin/python

Topic 2: Shell Tools. missing.csail.mit.edu .

Unlike other scripting programming languages, shell scripting is optimized for shell related tasks, e.g. reading from STDIN and saving results into files are primitives.

Pesky Whitespace

foo = bar
# Doesn't work because it's interpreted as calling the foo program with the args '=' and 'bar'
foo=bar # Now that works!

Literal Strings vs. Substitutable Strings

Single quotes are literal strings, but double quotes allow variable substitution.

Version Control Systems track changes to a folder and its contents in a series of snapshots. Each snapshot encapsulates the entire state of files/folders within a top-level directory.

Git’s interface is a leaky abstraction. While the interface is at times ugly, its underlying design and ideas are beautiful. A bottom-up explanation of Git therefore makes more sense.

Personalizing Your Shell

Put all of your scripts in the ~/bin/ directory, and add ~/bin/ to your path. Beware of conflicting with system commands. One alternative is to prefix your commands with a comma.

References

1. Start all of your commands with a comma. Brandon Rhodes. rhodesmill.org . news.ycombinator.com . Aug 18, 2009.